Obama to announce defense secretary nominee Friday

President Obama will announce his nominee for the next Defense Secretary at the White House on Friday, White House spokesman Josh Earnest told reporters Thursday.

The nominee is expected to be former Deputy Defense Secretary Ashton Carter, who became the sole focus of White House efforts to fill the post earlier this week.

If nominated and confirmed by the Senate to replace outgoing Defense Secretary Chuck Hagel, who resigned last month, Carter would be President Obama's fourth secretary of defense.

Carter was deputy secretary of defense between 2011 and 2013, serving as the Pentagon's chief operating officer under both Hagel and Hagel's predecessor, Leon Panetta. Before that, he'd served in a variety of roles within the Pentagon under Mr. Obama and former President Bill Clinton, along with lengthy stints in academia and the private sector.

• Defense Secretary Chuck Hagel resigning
• Ashton Carter expected to be nominated for Secretary of Defense this week

As the number two at the Pentagon, Carter helped oversee the department's budget during a period of belt-tightening, and he boasts a deep familiarity with the department and its massive bureaucracy that could be a selling point for his nomination. He stepped down in 2013 after Mr. Obama passed over him to nominate Hagel when Panetta retired.

Carter is viewed as a strong, known commodity in defense circles, respected by senior military leaders and well-known within the Pentagon civilian bureaucracy. Carter is also seen within the White House as an upgrade over Hagel in terms of strength of personality, confidence and vision on current national security challenges in the Middle East -- specifically coalition efforts to defeat the Islamic State of Iraq and Syria (ISIS).

Mr. Obama's next defense secretary will take the the helm of the Pentagon as it is facing multiple crises abroad, ranging from the rapid rise of ISIS to ongoing international talks to curb Iran's nuclear program and the spread of Ebola in West Africa. Additionally, Mr. Obama has quietly moved to expand the U.S. military rolein Afghanistan in 2015.

In the interim, defense and communications experts have been assisting Carter as he prepares for a possible nomination - specifically Jeremy Bash, former chief of staff to Leon Panetta in his roles as Defense Secretary and CIA Director, and Philippe Reines, a communications specialist with long-standing ties to former Secretary of State Hillary Clinton. Bash and Reines are founders of Beacon Global Strategies (where CBS News contributor Michael Morell is a senior counselor).

Carter's first challenge will be surviving the Senate confirmation process. After the new Republican-led Senate is sworn in next year, it will have to consider the nominations of both Carter and Loretta Lynch, Mr. Obama's nominee for attorney general. Should the new GOP leadership keep the current Senate rules, Mr. Obama's nominees will need the support of a simple 51-vote majority to be confirmed. Still, the confirmation votes set the stage for early political tension between Mr. Obama and the new GOP Congress.